Establishing connection across a connection-oriented first telecommunications network in response to a connection request from a second telecommunications network

ABSTRACT

A first multi protocol label switching (MPLS) enabled Internet Protocol (IP) data network is able to transmit data to a second MPLS enabled IP network via a legacy optical network, which would not otherwise be able to handle the user network interface (UNI) protocols required to be used within an MPLS network environment, by means of configuring the legacy optical network and its traditional network management system (TNMS) so that they simulate or emulate an MPLS enabled optical network. The simulation/emulation of an MPLS network is performed as follows: when a first legacy network element (NE) receives a connection request (a UNI request) from the MPLS network under a UNI protocol, the UNI request is passed to the TNMS, which then sets the required connection across the legacy network via a second edge NE to an NE of the second IP network. Once the connection has been set, the TNMS instructs the edge NE to send a return signal to the requesting network indicating that the connection has been successfully set. Data packets may then be transmitted across the network.

BACKGROUND OF THE INVENTION

The present invention relates to a method of communicating across atelecommunications network and associated apparatus. In particular, theinvention relates to a method of communicating across atelecommunications network, to a telecommunications network, to anetwork management system for setting connections in a network and to anetwork element of such networks.

Telecommunications networks, particularly optical networks, have in thepast routed data across the network by setting routes by means of amanually operated network management system. When changes are requiredto be made to the route or routes set in the network, response times canbe very long in comparison to the rate of transmission of data.

Significant improvements in routing of data have been made in recentyears in the context of electrical networks. One such improvement is theability of network elements of the network to route data packets withoutreverting to a separate network management system. Recently, the use ofMulti Protocol Label Switching (MPLS), which is currently used in bothIP and ATM networks, has been recognised as being particularlyadvantageous. One of the benefits of MPLS is that network elements ofthe network are able to route a given data packet quickly, by referenceto a label in the data packet. Furthermore, since the routing of datapackets does not require the exchange of data with a network managementsystem the use of MPIS has a major advantage in that it facilitatesdynamic network control without the delays often associated withnetworks controlled by a network management system.

It has been proposed, so as to facilitate dynamic network control, tointroduce MPLS, in the form of a Generalised Multi-protocol LabelSwitching (GMPLS) method, into optical networks. However, incorporatingGMPLS into an optical network is not straightforward. Two proposals havebeen made for implementing GMPLS in an optical network as will now bedescribed.

The first proposal may be referred to as the “Peer-to-Peer Model” and isillustrated by FIG. 1 of the accompanying drawings. With reference toFIG. 1, a first IP network 1 is connected via an optical network 2 to asecond IP network 3. The optical network 2 is required to make availableto the IP networks 1, 3 topological information (in the form of IPinformation) so that data packets can be routed from the first IPnetwork 1 to the second IP network 3 via the optical network 2 by meansof IP data in the data packet. If the optical network 2 is privatelyowned, making such topological information publicly available mayhowever be undesirable. For example, such information may be consideredto be commercially sensitive and it may be desired to keep suchinformation confidential.

The second proposal, which may be referred to as the “Client-ServerModel”, does not require the optical network to make public suchtopological information. In this second proposal, which is describedwith reference to FIG. 2 of the accompanying drawings, a first IPnetwork 1 is connected via an optical network 2 to a second IP network 3in a manner similar to that of the first proposal. However, in thisproposal the interfaces between the first and second IP networks 1, 3(the clients) and the optical network 2 (the server) each include a usernetwork interface 4 (UNI). Thus the first IP network 1, via a first UNI4 a, effectively request a connection across the optical network 2 bymeans of IP data in a data packet. Topology information relating to theoptical network 2 is however not made available outside the opticalnetwork 2.

Both of the proposals described above suffer from a significantdisadvantage. In order for the optical network to operate in a GMPLSenvironment it is necessary, in the proposals made, for the networkelements of the optical network to process and handle network topologyinformation and to set up and tear down network connections. In orderfor the individual network elements to be able to perform such tasks thenetwork elements each require significant processing capability andaccess to significant amounts of memory. Whilst such requirements can bemet when installing new optical networks, many existing optical networkelements are not able to perform at the required level. Replacing suchexisting optical networks (often referred to as legacy networks) wouldbe costly and is therefore undesirable.

BRIEF SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a methodof communicating across a telecommunications network which allows agiven protocol, for example a protocol used in an MPLS environment, tobe used in combination with other networks, for example opticalnetworks, and which mitigates one or more of the problems associatedwith the above-mentioned proposals. The present invention also seeks toprovide suitable means or apparatus for performing such a method oraspects of such a method.

According to a first aspect of the invention there is provided a methodof operating a connection-oriented communications network, thecommunications network comprising a plurality of network elements inwhich connections across the network elements are established by anetwork management system; the communications network being connectableto a second communications network by an edge network element, thesecond communications network comprising a plurality of network elementseach of which is capable of making connections or routing data acrossthe second network in accordance with a connection request received bythe element; the connection request being in accordance with apredetermined protocol, the method being for establishing a connectionacross the connection-oriented network in response to a connectionrequest from the second network and characterized by: the edge networkelement upon receiving a connection request from the second network,sending to the network management system information relating to theconnection request; the network management system sending signals to seta connection across the network in response to said information receivedfrom the edge network element; and the network management system causingthe edge network element to send a return signal according to thepredetermined protocol to the second network indicating the status ofthe setting of a connection.

The method of the present invention enables a connection-orientednetwork to establish connections in response to connection requests,which it would otherwise be unable to handle, by the steps of passingthe connection request from a suitably configured edge network elementto a suitably configured network management system, which is able toprocess the request, make the connection in accordance with the requestand respond via the edge network element in accordance with the givenprotocol. As far as the second network is concerned theconnection-oriented communications network is able to communicate withit under the given protocol. In the context of the method of theinvention, the manner in which connection requests are made can beconsidered as being a client-server arrangement, in which theconnection-oriented network is the server network and the second networkis the client network.

The return signal indicating the status of the setting of the connectionmay for example indicate either that the connection has beensuccessfully made or that the connection could not be made. After thesecond network receives a return signal indicating that the connectionhas been successfully made, data can then be transmitted from the secondnetwork across the communications network.

Advantageously the connection-oriented communications network is furtherconnectable to a third communications network by a further edge networkelement, the third network comprising a plurality of network elementseach of which is capable of making connections or touting data acrossthe third network in accordance with a connection request received bythe element, and the method further comprises: the network managementsystem causing the further edge network element to send a connectionrequest according to the predetermined protocol to the third networkthereby enabling connection of the second and third networks via theconnection-oriented network.

Preferably the connection-oriented network is operated such that, inuse, topology information relating to the network is not made availableoutside the network to for example the second and/or third networks. Ofcourse, information concerning the possible connections to and fromnetwork elements within, but at the edge of the network, may be madeavailable to network elements outside the communications network andaccordingly such information may be considered as not relating totopology information relating to the communications network.

Advantageously the predetermined protocol is a user network interface(UNI protocol The UNI protocol may be such that topology information isnot revealed over the interface between the communications networks. Theuser network interface protocol used may, for example, be in accordancewith the standards laid down by the Optical Interface Forum (OIF). Anappropriate standard is described in document number OIF 2000.125available from the Optical Interface Forum. In the case where thecommunications network is connected to MPLS enabled networks, thearrangement may be such that the MPLS network elements require aconnection request in order to make a connection and transmit data. SuchMPLS network elements may also be arranged automatically to sendappropriate connection requests. Thus, when setting a connection fromthe communications network to the third network that is MPLS enabled,the network management system advantageously causes the further edgenetwork element to send an appropriate connection request, for example,a UNI request.

The method may be such that other protocols are used when furtherconnection requests are made between network elements of the network.For example, a network network interface (or NNI) protocol may be used.An NNI protocol may be especially convenient when connection requestsare made between MPLS enabled network elements. The NNI protocol may besuch that topology information is revealed over the interface betweenthe relevant network elements.

According to a second aspect of the invention there is provided aconnection-oriented communications network comprising a plurality ofnetwork elements in which connections across the network elements areestablished by a network management system; the communications networkbeing adapted to be interoperable with a second communications networkby an edge network element, the second network comprising a plurality ofnetwork elements each of which is capable of making connections orrouting data across the second network in accordance with a connectionrequest received by the element; the connection request being inaccordance with a predetermined protocol, the connection-orientednetwork being characterized by the edge network element upon receivingconnection request from the second network, sending to the networkmanagement system information relating to the connection request; thenetwork management system sending signals to the network elements to seta connection across the network in response to said information receivedfrom the edge network element; and the network management system causingthe edge network element to send a return signal according to thepredetermined protocol to the second network indicating the status ofthe setting of a connection.

The present invention finds particular application to legacyconnection-oriented networks that comprise network elements unable tomake connections or route data in accordance with connection requests.The step in which the edge network element sends to the networkmanagement system information relating to the connection request cancomprise relaying, or repeating, the connection request. The edgenetwork element may therefore be required to perform little orpreferably no processing of the connection request. Conveniently theedge network element can comprise a legacy edge network element that hasbeen appropriately adapted. Conversion of the legacy network element mayinclude a step of programming the network element with appropriateupdated software. The requirements of such computer software will beapparent to the relevant persons skilled in the art and, as such,further details of such software are not provided here. Alternatively,the conversion could be made by means of extra hardware in addition to,or instead of, providing such software.

The network management system advantageously comprises the legacynetwork management system that has been appropriately adapted. Theconversion of such a legacy network management system may include a stepof programming the network management system with appropriate updatedsoftware. Again the requirements of such computer software would beapparent to those skilled in the art, when presented with the details ofthe present invention. Alternatively, the conversion could be made bymeans of extra hardware in addition to, or instead of, providing suchsoftware.

Advantageously the communications network further comprises a furtheredge network element for connecting the communications network to athird communications network, the third network comprising a pluralityof network elements each of which is capable of making connections orrouting data across the third network in accordance with a connectionrequest received by the element, the network management system beingconfigured to cause the further edge network element to send aconnection request according to the predetermined protocol to the thirdnetwork thereby enabling connection of the second and third networks viathe communications network. Such a network is advantageous where thethird network requires a connection request according to thepredetermined protocol to be received before a connection can be made.Since the network management system causes the further edge network tosend the connection request this eliminates the need for the furtheredge network element to be able to itself generate the connectionrequest.

Preferably the communications network is operated such that, in use,topology information relating to the network is not made availableoutside the network.

Advantageously the predetermined protocol is a user network interface(UNI) protocol. The network management system may also be able to handlethat some UNI protocol insofar as is necessary to enable it to cause theedge network element to send the return signal under the same UNIprotocol. The relevant edge network elements of the network may simplybe programmed with appropriate software to enable them to handle thesame UNI protocol.

Preferably the second and/or third networks are packet based networks,such as Internet Protocol (IP) networks in which data packets are routedby the network elements in dependence upon the connection request withinthe packets. Alternatively the second and/or third networks can compriseAsynchronous Transfer Mode (ATM networks, and alike, in whichconnections are established by the network elements in dependence uponconnection requests. The invention finds particular application forconnection to networks able to handle Multi-Protocol Label Switching(MPLS). It will be understood that multi-protocol label switching maytake many forms, any of which could be used in the context of thepresent invention. For example, a generalised form of MPLS (GMPLS) maybe used The form of multi-protocol label switching used may however beconveniently chosen to be in accordance with an accepted standard, forexample a standard set by the Internet Engineering Task Force.

According to a farther aspect of the invention there is provided an edgenetwork element for use in a communications network in accordance withthe second aspect of the invention.

According to a yet further aspect of the invention there is provided anetwork management system for use in a communications network inaccordance with the second aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofexample only with reference to the accompanying schematic drawings, ofwhich:

FIGS. 1 and 2 show prior art proposals for a telecommunications network;

FIG. 3 illustrates a telecommunications network in accordance with afirst embodiment of the invention; and

FIG. 4 illustrates a telecommunications network in accordance, with asecond embodiment of the invention.

FIGS. 1 and 2 relate to prior art proposal and are described above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A telecommunications network according to the first embodiment of theinvention is shown in FIG. 3. With reference to FIG. 3 the networkincludes a first MPLS enabled IP network 11 connectable to a second MPLSenabled IP network 13 via a legacy optical network 12. The legacyoptical network 12 includes a plurality of internal network elements 15(only one of which is shown in FIG. 3 for the sake of clarity) and aplurality of edge network elements 14 a, 14 b (only two of which areshown). The legacy optical network 12 is also connected to a traditionalnetwork management system 16.

At the interface between the first IP network 11 and the optical network12, signals may be received and sent by an edge network element 14 a ofthe optical network 12. Similarly, at the interface between the secondIP network 13 and the optical network 12, signals may be received andsent by an edge network element 14 b of the optical network 12. Networkaccess and connection requests may be made through the edge networkelements of the optical network. The network may thus be considered asforming a client/server system with interfaces, between the server (theoptical network 12) and the client (the first or second IP networks 11,13).

The protocol used at such interfaces, in relation to the provision ofnetwork access and connection requests, is a UNI (user networkinterface) protocol.

A UNI protocol is also used throughout the first and second IP networks11, 13 and connection requests in the form of UNI requests are, in theIP networks, processed by the local network elements, connections beingestablished by use of the topology protocols running across the network.The topology protocols used may for example be an OSPF (Open ShortestPath First) protocol. However, the network elements within the legacyoptical network 12 are not able to process such requests locally. Themaking of a connection across the optical network 12, including thehandling of UNI requests made to edge network elements of the opticalnetwork 12, will now be described.

A UNI request is sent to a first edge network element 14 a of theoptical network 12 from a network element (not shown separately) of thefirst IP network 11, the request effectively requesting a connection toa network element of the second WP network 13. The request is sent(arrow A) directly to the network management system 16. The networkmanagement system 16 then processes the request and determines anappropriate connection across the optical network 12. The networkmanagement system 16 then sends signals (arrows B) instructing the edgenetwork element 14 a, the relevant internal network elements 15 and asecond network element 14 b of the optical network to establish therequired connection. The network management system 16 then formulates asuitable response for sending to the network element of the firstnetwork 11 that sent the UNI request. The network management system 16then sends (arrow C) a signal to the edge network element 14 aoriginally receiving the UNI request, causing that edge network element14 a to send such a suitable response to that network element of thefirst network 11.

The response sent from the edge network element 14 a originallyreceiving the UNI request to the network element of the first network 11indicates either that a connection has been successfully made or thatthe connection failed, as appropriate. If the connection is successfullymade the network element of the first network 11 is then able to senddata via the optical network 12 to the appropriate network element ofthe second IP network 13.

The IP networks 11, 13 are not able to discover the topology of theoptical network 12, as such information is not made available outside ofthe optical network 12.

Thus it will be appreciated that such an arrangement enables aclient/server UNI network to be established without the need for networkelements of the server network (the legacy optical network 12) to runlocally any topology protocols. This is especially advantageous inlegacy networks, such as the optical network 12 illustrated in FIG. 3,where the network elements do not have the required memory and/orprocessing power to handle such protocols.

A telecommunications network according to a second embodiment of theinvention is illustrated with reference to FIG. 4. In this secondembodiment, MPLS enabled network elements are combined with legacynetwork elements in a common transport network. The MPLS enabled partsof the network can operate with full topology protocols, whereas thelegacy part of the network effectively emulates a UNI interface toenable connections across the legacy part of the network to be providedautomatically on request.

With reference to FIG. 4, the network includes a first MPLS enabled IPnetwork 21 a connectable to a second MPLS enabled IP network 23 a via anoptical network 20. The optical part of the network comprises a legacyoptical network 22 connectable between first and second MPLS enabledoptical networks 21 b, 23 b. The legacy optical network 22 includes aplurality of internal network elements (not shown) and a plurality ofedge network elements 24 a, 24 b and is connected to a traditionalnetwork management system 26, in a manner similar to that of the legacyoptical network 12 shown in FIG. 3.

In FIG. 4, the first IP network 21 a has a UNI interface to the opticalnetwork 20. Topology information relating to the first MPLS opticalnetwork 21 b, the second MPLS optical network 23 b and the legacyoptical network 22 is not made available outside each network,respectively. As far as the first IP network 21 a is concerned theoptical network 20 may, or may not, be separated into MPLS enabled andlegacy optical networks. The making of a connection from the first IPnetwork 21 a to the second IP network 23 a will now be described.

The first IP network 21 a sends a UNI request to the first MPLS enabledoptical network 211 b of the optical network 20, the UNI requesteffectively, requesting a connection to a network element (not shownseparately) of the second IP network 23 a via the optical network 20.The UNI request is processed locally within the first MPLS opticalnetwork 21 b, and the requested connection made to the edge of thatnetwork, where it meets another UNI interface (the interface between thefirst MPLS optical network 21 b and the legacy optical network 22). Anew UNI request is therefore sent from an edge network element of thefirst MPLS optical network 21 b to a first edge network element 24 a ofthe legacy optical network 22. This UNI request effectively requests aconnection from the interface between the MPLS optical network 21 b andthe legacy optical network 22 to the destination network element of thesecond IP network 23 a. Since the network receiving the UNI request is alegacy optical network 22, the request cannot be processed locally bythe network elements of the network 22.

In a manner similar to that described above with reference to the firstembodiment, the request is sent (arrow A) directly to the traditionalnetwork management system 26. The network management system 26 thenprocesses the request and determines an appropriate connection acrossthe optical network 22. The network management system 26 then sendssignals (arrow B) instructing the edge network element 24 a, therelevant internal network elements and a second network element 24 b ofthe optical network to establish the required connection. In thisembodiment, however, the legacy optical network 22 interfaces to anotheroptical network, which is MPLS enabled (i.e. the second MPLS opticalnetwork 23 b).

The second MPLS optical network 23 b requires a UNI request to cause itto make the connection to the second IP network 23 a. Thus the networkmanagement system 26 sends (arrow X) to the second edge network element24 b of the legacy network 22 a signal causing the second edge networkelement 24 b to send a UNI request to an edge network element of thesecond MPLS optical network 23 b. This UNI request again effectivelyrequests a connection to be made to the destination network element ofthe second IP network 23 a. The UNI request is processed locally withinthe second MPLS optical network 23 b, and the requested connection madeacross that network to the destination network element of the second IPnetwork 23 a.

The edge network element of the second MPLS optical network 23 breceiving the UNI request from the second edge network element 24 b ofthe legacy network 22, sends a return signal under the UNI protocol tothe second edge network element 24 b, the return signal indicating thatthe requested connection has been successfully made. The return signalis sent (arrow Y) directly to the network management system 26. Onreceipt of that return signal the network management system 26formulates a suitable response for sending to the network element of thefirst MPLS optical network 21 b that sent the UNI request to the legacynetwork 22. The network management system 26 then sends (arrow C) asignal to the edge network element 24 a originally receiving the UNIrequest from the first MPLS optical network 21 b, causing that edgenetwork element 24 a to send such a suitable response under the UNIprotocol to the relevant edge network element of the first MPLS opticalnetwork 21 b.

The indication of the successful connection is then finally relayed tothe first IP network 21 a by the first MPLS optical network 21 b tocomplete the connection process. The network element of the first IPnetwork 21 a is then able to send data via the optical, network 20 tothe appropriate network element of the second IP network 23 a. Shouldthe process fail at any stage, then a failure response is sent back tothe requesting network. The network is arranged such that on such afailure any intermediate connections that have been made in relation tothe given connection request are cleared down.

As will be appreciated, various modifications may be made to the abovedescribed embodiments. For example, two IP networks could be connectedvia an optical network, such that a first IP network is connected to asingle MPLS optical network, which is connected to a single legacynetwork, which is connected to a second IP network. In such a case, thereceipt from the first network of a UNI request requesting connection tothe second IP network would be handled in a similar manner to thatdescribed with reference to the first embodiment. The UNI request passedon by the MPLS optical network would be passed from an ingress legacynetwork element to the network management system of the legacy network,which would set a connection across the legacy network to the second IPnetwork, and then cause the ingress legacy network element to send anappropriate response to the requesting IP network, data thereafter beingtransmitted from the first IP network across the optical network and tothe second IP network.

Also, two IP networks could be connected via an optical network, suchthat a first IP network is connected to a single legacy network, whichis connected to a single MPLS optical network, which is connected to asecond IP network. In such a case, the receipt from the first network ofa UNI request requesting connection to the second IP network would behandled in a similar manner to that described with reference to thesecond embodiment. The UNI request would be passed from an ingresslegacy network element to the network management system of the legacynetwork, which would set a connection, send a UNI request via an egresslegacy network element to the MPLS optical network, receive anappropriate response via the egress legacy network element from the MPLSoptical network, and then cause the ingress legacy network element tosend an appropriate response to the requesting IP network, datathereafter being transmitted from the first IP network across theoptical network and to the second IP network.

Other permutations of legacy optical, optical MPLS, and IP networks willof course be apparent to those skilled in the art.

Whilst MPLS optical networks have been referred to above, theembodiments described would of course also be of use if the MPLS opticalnetworks were in the form of GMPLS (generalised MPLS) optical networks.

The IP based networks described above need not be IP data networks andcould alternatively be ATM data networks, since such networks may alsobe used with MPLS and user network interfaces (UNI)

The topology protocols used across the MPLS networks need not be OSPF.For example, the topology protocol used may alternatively be an IS/IS(Intermediate System to Intermediate System Routing Exchange) protocolfrom the OSI (Open Systems Interconnection).

1. A method of operating a connection-oriented first communicationsnetwork having a plurality of first network elements in whichconnections across the first network elements are established by anetwork management system, the first network being connectable to asecond communications network by an edge network element, the secondnetwork having a plurality of second network elements each operative formaking connections or routing data across the second network inaccordance with a connection request received by the edge networkelement, the connection request being in accordance with a predeterminedprotocol, the method being performed to establish a connection acrossthe connection-oriented first network in response to the connectionrequest from the second network, and comprising the steps of: a) uponthe edge network element receiving the connection request from thesecond network, sending to the network management system informationrelating to the connection request; b) sending signals by the networkmanagement system to set the connection in response to said informationreceived from the edge network element; and c) causing the edge networkelement by the network management system to send a return signalaccording to the predetermined protocol to the second network indicatinga status of a setting of the connection.
 2. The method according toclaim 1, wherein the connection-oriented first network is furtherconnectable to a third communications network by a further edge networkelement, the third network having a plurality of third network elementseach operative for making connections or routing data across the thirdnetwork in accordance with a connection request received by the furtheredge network element, the method further comprising the step of: causingthe further edge network element by the network management system tosend a connection request according to the predetermined protocol to thethird network, thereby enabling a connection of the second and thirdnetworks via the connection-oriented first network.
 3. The methodaccording to claim 1, and comprising the step of operating theconnection-oriented first network such that, in use, topologyinformation relating to the first network is not made available outsidethe first network.
 4. The method according to claim 1, wherein thepredetermined protocol is a user network interface (UNI) protocol.
 5. Aconnection-oriented first communications network, comprising: aplurality of first network elements in which connections across thefirst network elements are established by a network management system,the first communications network being interoperable with a secondcommunications network by an edge network element, the second networkhaving a plurality of second network elements each operative for makingconnections or routing data across the second network in accordance witha connection request received by the edge network element, theconnection request being in accordance with a predetermined protocol,the edge network element upon receiving the connection request from thesecond network, being operative for sending to the network managementsystem information relating to the connection request, the networkmanagement system being operative for sending signals to the firstnetwork elements to set a connection in response to said informationreceived from the edge network element, and the network managementsystem being operative for causing the edge network element to send areturn signal according to the predetermined protocol to the secondnetwork indicating a status of a setting of the connection.
 6. Theconnection-oriented first communications network according to claim 5,and further comprising a further edge network element for connecting thefirst network to a third communications network having a plurality ofthird network elements each operative for making connections or routingdata across the third network in accordance with a connection requestreceived by the further edge network element, the network managementsystem being configured to cause the further edge network element tosend the connection request according to the predetermined protocol tothe third network, thereby enabling the connection of the second andthird networks via the first network.
 7. The connection-oriented firstcommunications network according to claim 5, wherein the first networkis operated such that, in use, topology information relating to thefirst network is not made available outside the first network.
 8. Theconnection-oriented first communications network according to claim 5,wherein the predetermined protocol is a user network interface (UNI)protocol.
 9. The connection-oriented first communications networkaccording to claim 5, wherein the first network is an opticalcommunications network.
 10. The connection-oriented first communicationsnetwork according to claim 5, wherein the second network elements of thesecond network are operative for establishing connections or routingdata in accordance with multi-protocol label switching (MPLS).
 11. Amethod of operating a first communications network having a plurality offirst network elements and a network management system, whereinconnections across the first network elements are established by thenetwork management system, the first network being connectable to asecond communications network by an edge network element, the secondnetwork having a plurality of second network elements each operative formaking connections or routing data across the second network inaccordance with a connection request received by the edge networkelement, wherein the first and second networks use different switchingor routing techniques, the connection request being in accordance with apredetermined protocol, the method being performed to establish aconnection across the first network in response to the connectionrequest from the second network, and comprising the steps of: a) thenetwork management system receiving information relating to theconnection request from the edge network element; b) the networkmanagement system sending signals to set the connection in response tosaid information received from the edge network element; and c) thenetwork management system sending a signal to the edge network elementto cause the edge network element to send a return signal according tothe predetermined protocol to the second network indicating a status ofa setting of the connection.
 12. The method according to claim 11,wherein a connection request is made in a client-server arrangement, inwhich the first communications network is a server network and thesecond network is a client network.
 13. The method according to claim11, wherein the first communications network is a connection-orientednetwork.
 14. An edge network element for use in a connection-orientedfirst communications network having a plurality of first networkelements in which connections across the first network elements areestablished by a network management system, the edge network elementbeing characterized in that: the edge network element is operative forconnecting the first communications network to a second communicationsnetwork having a plurality of second network elements, the edge networkelement is operative for receiving a connection request in accordancewith a predetermined protocol, each of the plurality of second networkelements being operative for making connections or routing data acrossthe second communications network in accordance with the connectionrequest, wherein the edge network element is, in order to establish aconnection across the connection-oriented first network, configured toreceive the connection request from the second communications network,and to send information relating to the connection request to thenetwork management system, and to receive a signal from the networkmanagement system, and the received signal causing the edge networkelement to send a return signal, according to the predetermined protocolto the second communications network, indicating a status of a settingof the connection established by the network management system, andwherein the connection is established by the network management systemsending signals to set the connection in response to informationrelating to the connection request received from the edge networkelement.
 15. A network management system, characterized in that: thenetwork management system establishes connections across a plurality offirst network elements of a connection-oriented first communicationsnetwork, the connection-oriented first communications network beingconnectable to a second communications network having a plurality ofsecond network elements by an edge network element, each of theplurality of second network elements being operative for makingconnections or routing data across the second communications network inaccordance with a connection request in accordance with a predeterminedprotocol received by the edge network element, wherein the networkmanagement system is, in order to establish a connection across theconnection-oriented first communications network, configured to receiveinformation relating to the connection request from the edge networkelement, the edge network element receiving the connection request fromthe second communications network, and wherein the network managementsystem is further configured to send signals to set the connection inresponse to the received information, and to send a signal to the edgenetwork element to cause the edge network element to send a returnsignal according to the predetermined protocol to the secondcommunications network, and the return signal indicating a status of asetting of the connection.